42 PEARLS [CH. 



CHAPTER IV 



THE LIFE-HISTORY OF THE PEARL OYSTER, AND 

 THE CONDITIONS UNDER WHICH IT LIVES 



The mature pearl oysters, as we have seen, dis- 

 charge into the sea their sexual products, eggs or 

 spermatozoa, according to the sex. The actual 

 emission has been observed in May for Ceylon 

 oysters, but probably the spawning season extends 

 over many months of the year. 



The eggs and spermatozoa pass out direct from 

 the reproductive organs into the water, which is con- 

 tinually passing into and out of the pallial cavit}. 

 Fertilisation of the eggs takes place in the sea- water. 

 There is however a very great probability, as the 

 author has observed in the case of other lamelli- 

 branchs, that the emission of ripe spermatozoa from 

 the male is stimulated by the presence of female 

 oysters. 



As the pearl oyster is a gregarious animal like 

 our own edible mussel, there is every chance of the 

 numerous eggs being fertilised, even though no act 

 of copulation brings the sexual products together. 

 This method of fertilisation of the eggs may be taken 

 as holding good for the other relatives of the Ceylon 

 Pearl Oyster — the Mother-of-Pearl Oysters — and also 



